Commands run:
go mod init
go mod tidy
sed -i 's/go 1.12/go 1.11/' go.mod
go test ./...
Fixes#355
Change-Id: I196d77e9c15a2780e2649e735520578c01191a1b
Reviewed-on: https://go-review.googlesource.com/c/157137
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>